2006-10-24 07:12:38 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
This is the Car Talk puzzler.
Thinking backwards, the last mile will take 1 hour (1 mile at 1 mph). The penultimate mile will take 1/2 hour (1 mile at 2 mph), the mile before will take 1/3 hour (1 mile at 3 mph), etc. all the way up to 1/75 hour (1 mile at 75 mph).
This works out to 1/1 + 1/2 + 1/3 + 1/4 + ... + 1/74 + 1/75.
This is a diverging harmonic series, but for this limited range, you can add up all the fractions.
It comes out to 4.91 hours or approx. 5 hours. It helps to have a spreadsheet or a calculator to figure this out...
2006-10-24 07:15:28 · answer #1 · answered by Puzzling 7 · 2⤊ 0⤋
A very long time. The last mile alone would take you 60 minutes.
2006-10-24 14:15:54 · answer #2 · answered by Anonymous · 0⤊ 0⤋
I don't care -I doing a 100 mph and getting there fast.
2006-10-24 14:14:37 · answer #3 · answered by super stud 4 · 0⤊ 1⤋
4.9 hours
2006-10-24 17:29:44 · answer #4 · answered by Mellow F 1 · 1⤊ 1⤋